<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

</head>
<body>
    <input type="text" id="username"> <input type="checkbox" name="" id="remeber">记住用户名
    <script>
        var username = document.querySelector('#username');
        var remeber = document.querySelector('#remeber');
        if(localStorage.getItem('username')){
            username.value = localStorage.getItem('username');
            remeber.checked = true;
        }
        remeber.addEventListener('change', function(){
            if(this.checked){
                localStorage.setItem('username', username.value)
            }else{
                localStorage.removeItem('username');
            }
        })
    </script>
</body>
</html>